storm

storm, disturbance of the ordinary conditions of the atmosphere attended by wind, rain, snow, sleet, hail, or thunder and lightning. Types of storms include the extratropical cyclone, the common, large-scale storm of temperate latitudes; the tropical cyclone, or hurricane, which is somewhat smaller in area than the former and accompanied by high winds and heavy rains; the tornado, or "twister," a small but intense storm with very high winds, usually of limited duration; and the thunderstorm, local in nature and accompanied by brief but heavy rain showers and often by hail. The term storm is also applied to blizzards, sandstorms, and dust storms, in which high wind is the dominant meteorological element.

A storm surge, sometimes called a tidal wave, is a flood of ocean or lake water that occurs in areas subject to tropical storms and bordering on shallow waters, but any strong low-pressure system in a coastal area, such as a northeaster along the Atlantic coast of North America, may produce a storm surge. Storm surges are due mostly to wind, which pushes the water ahead of a storm. In Galveston, Tex., in 1900 a hurricane with a wind velocity of more than 100 mi (160 km) per hr caused an ocean storm surge 15 ft (5 m) above normal high tide levels that flooded coastal areas, resulting in the loss of thousands of lives and extensive property damage. The highest storm surge on record in the United States is that caused by Hurricane Katrina (2005), which had sustained winds at landfall in SE Louisiana of more than 140 mi (225 km) per hr and a storm surge that by one estimate reached 29 ft (8.8 m) on the SW Mississippi coast and caused coastal devastation from SE Louisiana to Alabama.